1. Field of the Invention
The present invention relates to a package of moisture-controlled glass articles, and more particularly, concerns a package of glass microscope slides into which moisture is prevented from entering and pre-existing moisture within is removed at a controlled rate.
2. Description of the Prior Art
Packaged glass articles, and specifically flat, thin glass microscope slides, have a tendency to lose their visual clarity when being stored before use. In addition, and particularly with flat, thin glass articles, storage tends to cause these glass articles to stick together rendering them difficult to separate after the package is opened. When the glass articles of concern are glass microscope slides, it is appreciated that visual deterioration of the glass surfaces is unacceptable since it may interfere with the observer's ability to properly view the substances contained on the slides.
It is believed that moisture acting on the surfaces of glass articles, such as microscope slides, produces a chemical reaction which deteriorates the surfaces causing them to appear dirty and oily. Once this surface deterioration occurs, it undesirably causes the glass slides, which are packaged in a surface-to-surface arrangement, to stick together. The deterioration of the glass surfaces is initiated by moisture (H.sub.2 O) in its ionic form contacting the glass surfaces. A hydrogen donor is given up by the H.sub.2 O to the glass matrix thereby producing the chemical conditions to form sodium hydroxide. A white film then forms out of other substances that are available from the breakdown of the glass structure and carbon dioxide present in the atmosphere. For example, and as a result of this breakdown, the formation of such materials as sodium carbonate and sodium bicarbonate is manifested in white powder form; sodium sulfate and silicic acid residues appears as light white haze on the surface of the glass. White powder and haze on the surfaces of the glass slides are undesirable and are observed as dirt by the user. Moreover, the white film and haze which accumulates may be scraped loose and become intermixed with the sample material placed on the surface of the slide. As a result, the undesirable white powder and haze interferes with the visual examination and subsequent diagnosis of specimens on the surface of a glass microscope slide.
When moisture accumulates on the surfaces of the slides and initiates the glass breakdown process, it also causes a sticking effect. This sticking effect is due to the flat surfaces of the slides in face-to-face arrangement which renders them difficult to separate particularly on an individual basis. It should be kept in mind, however, that the accumulation of moisture on the surfaces of glass microscope slides is not totally undesirable. Specifically, the presence of some moisture on the glass surfaces causes a chemical reaction which increases the surface lubricity thereof, rendering the slides more slippery. A slippery glass surface on a microscope slide, but one which has not visually deteriorated, facilitates the process of blood smear procedures in diagnostic laboratories. Therefore, in many instances, it is desirable to strike a balance between the removal of moisture from packages to obviate the visual deterioration of the glass and the retention of some moisture to render increased lubricity to the glass surface.
With the foregoing in mind, it can be seen that significant improvements in the packaging of glass articles, such as microscope slides, are desired and are still being sought. Accordingly, the present invention is directed toward the solution of the aforementioned problems and desired goals.